We used orange extract. It was back in college with the mad scientists club. He was stirring the molten sugar mix right after adding the flavor when a spark must've gone off. I didn't really know much about flashpoint safety at the time.
A very large flame grew over the pot and under his arm in an instant. At first it didn't look so bad, just some singed arm hairs and redness, but after an hour I realized it needed some professional attention. It happened in my apartment so I felt responsible. I was in the ER with him till almost 4 am (it happened at like 8 pm). He stuck around the club at first but then he stopped coming; he was a history major after all! He wasn't a close friend, but I saw him about 2 years later and he showed me the burn was completely healed and scar free! I was very happy to see that.
I have pictures of the burn backed up from my old phone if anyone really wants to see it. I'd have to dig it up!
Funny enough, this was with the same club that got me into soap. We (they) did a lot of stupid things. After the burn incident I tried to be the voice of reason when someone had a "great idea!"