Not everything is water-soluble. Water is a pretty impressive solvent but it's not alkahest so it certainly doesn't rip apart everything.

As to the actual dangers to organic life, cell membranes etc. being (unsurprisingly) not water soluble: The issue is osmotic pressure. The inside of the cells are salty, the outside less so, which means that water will travel from the area with lower concentration into that of higher concentration until both sides have the same saltiness.

If you're a microrganism with very limited capacity to get rid of that excess water and no mineral reserves you're going to burst. For the rest of us though it's a novel way to burn your tongue. You'll be fine I just burned mine on chilli beans though half of the feeling is probably the Szechuan pepper. No regrets.