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.
There was one time when I put a mold filled with liquid water in a cold container and made solid water.
Cooking & baking
baking bread
Extracted lsa from morning glory seeds in order to make my own knock-off lsd
Yeah, polar/non-polar extractions are about as far as my home chemistry got. But the LSA was good.