I certainly had the sinking sensation that it COULD easily be any one of our kids here, when I was reading this.
SciAm blog -How to repel kids from science: By shackling curiosity in cuffs
Sheesh. My DD and I were making bicarbonate-vinegar... er... IED's...
when she was about four. She loved figuring out the best ratio for propelling a film-canister cap the greatest distance, I might add.
Her father and I, both being chemists, saw
nothing wrong with this activity, and enthusiastically supported her desire for exploration.
I did make her don safety glasses, however.

I'm sure that that the fact that we were homeschooling at the time meant that we only had to worry about the neighbors, and not about imminent arrest or expulsion.