Phenol... ah, the nostalgia. As a teenager, I once added a drop of fuming nitric acid to some phenol. I understood that I may be able to make picric acid that way. I just didn't appreciate quite how unstable the resulting compound would be until the instant the acid hit the phenol and the glass beaker disappeared in the resulting detonation. I was not wearing googles (of course), and to this day I am thankful no glass hit my eyes. I'm also extremely thankful I only added a single drop of acid. Scary substances indeed!