There was one time when I put a mold filled with liquid water in a cold container and made solid water.

I take in oxygen and turn it into philosophical thought.

Extracted lsa from morning glory seeds in order to make my own knock-off lsd

I helped create life and It was orgasmic!

baking bread

Weed science. Not complicated at all, but there's so much bro science out there...

Eating.

I bake from scratch.

Closest I've come to Mad Scientist was probably yeast ranching to control costs in homebrewing.

• sterilize agar media and plates/tubes in poor man's autoclave (pressure coooker) and hood (open oven door and vent fan) - infection rates were surprisingly low with this low-tech approach. I lost maybe 5% of cultures to spurious growth.
• streak yeast from $$$ pure liquid cultures, grow, store if successful.
• also experimented with yeast suspensions in sterile distilled water based on a 1930s science journal article from a dude in Africa. The suspensions did better in the heat where agar would just remelt....
• a few days before needed scrape the streak into a small amount of sterile wort (20ml? on a homemade stirplate (PC fan and HD magnets under an unpended tupperware bowl!), stepping up to pitchable volume coinciding with the batch cooling to pitch temperature....

It was a lot of fun and instead of one 5gal batch of beer from an exotic $20 yeast sample you could get as many as you wanted. In practice I usually did 5-10 cultures from each pure sample. Could do more than that but there was a limit to how much stuff I could sterilize in my "autoclave" at one time.

Edited to add: I successfully cultured yeast from hefeweizen, but since what's in the bottle is typically for secondary/priming rather than primary it was only for fun. I had 100% failure trying to harvest wild yeast from the air or sampled from fruit skins. I couldn't isolate the yeast from other critters.

Probably something using dihydrogen monoxide as a solvent for a mixture of organic compounds

Steel etching with Winsteard's reagent. It is a bit dangerous because if done wrong it forms explosive dust. It was also long and tedious because the liquid must be near boiling and stirring so it evaporated quickly and has to be topped off and brought back to temperature often. The etch itself requires a long temper of a quenched sample and has an iterative process of etching and back-polishing to gradually remove surface roughness but leave the slightly deeper grain boundaries.

It took several hours of preparation and several hours of active work per sample and even then had a 50/50 success rate. I was professionally trained by a third party who learned this process from the person who perfected it, George Vander Voort.

For me it has been etching circuit boards and specifically making my own liquid tinning solution at one point. I mostly do hydrochloric acid/hydrogen peroxide on larger stuff and ferric chloride on smaller prototypes.

I'm surprised that nobody has done an extraction of organic/aromatic content in an oil/fat ? Have you never backed some "space cakes" ? I haven't but I've seen people doing it, and it's pretty advanced chemistry when you think well

I got old

I don't know if we can call it chemistry but quenching steel.

In high school I was doing blacksmithing and so quenching the blade was part of the process, probably my favorite part.

Heating the blade above 800°C and dipping it in oil, with the oil instantly catching fire was always very dramatic.

retrobrite of my fridge handles. hydrogen peroxide and uv light to remove yellowing

Extracted lidocaine from butt lube.

I remember we had a lot of fun with Benzene and Benzoates in university, but suspiciously I can't remember details. Hmmm

Definitely not nitrating cellulose. That would be irresponsible.

Pop Rocks, mouth, coca cola.

Made soap out of lye and a mix of fats and oils.

Stripped a cast iron pan using electrolysis, although that might be more physics than chemistry. I had to add Sodium Carbonate so that's pretty sciencey!

Made pH 14 lye to break down some plant cells and extract stuff. Then putting "surgical spirit" (I hate common english terms) in it to extract it, pipetted it carefully and let it evaporate.

Best DMT you can get :D

Mac n cheese

I once destiled water... from a but less impure water.

Cooking & baking

Baking soda and vinegar to clean stuff

I used to be an industrial chemist. We did esterification reactions to turn chicken fat and laxatives into oil field soaps by the truckload. So I guess mid-level organic chemistry?

Production of chlorine gas

Gold and Tellurium nanoparticle synthesis was the most interesting but I am not sure it qualifies as "complicated" given the procedures we used.

If computational chemistry qualifies, I have run on the order of 5,000 DFT optimizations+freq and of those, the most complicated ones involved metallocarborane clusters. These are composed of Boron, Carbon, a metal and different groups coming off the cluster. The largest one that I worked on took about a week to run the calculations on my home machine.

My great nephew as a teenager ran afoul of an old-school BBS archive website. He was certain it would be good fun to make a few incendiaries, Despite my attempts to dissuade him, he began to hide his enthusiasm, which had me worried he'd do it on his own. I figured it'd be wiser (and safer) to have someone with a bit of chemistry knowledge around when he tried doing dumb things.

We started small. I purchased some dry ice. Thermite was too boring. Elephant toothpaste was cool at first. Some petrol with polystyrene mixed in. Aluminium and acid cleaner. Then onto fertiliser tennis balls.

We eventually worked our way up to the Taj Mahal... Cyclonite. Hexogen. RDX. Unstable as the devil and more volatile than nitrated toluene, or TNT. The chemistry was very simple, but ridiculously foolish. I consider it advanced only due to the difficulty in ensuring we didn't get to visit a hospital or get a visit from the bobbies.

Never again. It took several days because I multiplied the recipe, like a dunce. We should've just made TNT, it would've been safer, but he persisted and I indulged.

The night before the big day. At this point, we'd been faffing around a dangerous line for almost ten months, whenever he managed to wrangle some free time for more mischief. I'd managed to extract a promise, this was to be the last of it until after his national service. He agreed. Keeping it in the boot of the car had me especially anxious,and until we saw the detonation, I felt like a long tailed cat in a room full of rocking chairs. The detonations in a desolate field were gratifyingly lovely though. He got the final trigger on an over sized charge, and his grin was worth the heartache.

He's a pharmacist now.

I work in a chemistry lab

Extraction and purification of surface residue for triple quadrupole analysis looking for pesticides, or inductively coupled plasma optical emission spectrometry looking for arsenic, but that's practically physics by that level.

I wrote a report on alkali-silica reactivity in concrete.

I used to run a bakery from home. We made pretzels with lye.

Titration of pool water to find its acidity using a commercial kit

Napalm from petrol and styrofoam

Acid assisted microwave digestion

Had to do a flame test to identify old fuel for recycling.

Made blue dye from indigo, and red and orange dye from madder, mixing in alum and other things. Making blue is amazing, it comes out green then changes colour all at once. Get the mix wrong and you get the wrong colour.... Also we boiled one batch of madder and got orange instead of scarlet, so even the temperature had to be regulated.

Most recently, been making etched plates from the inside of soft drink cans, etching with copper sulfate (they sell it in Bunnings as a fertiliser). Lots of fun!

So yeah mostly art projects.

That said even baking a cake is pretty fancy chemistry.