IMPORTANT SAFETY MESSAGE:
I would feel terrible if someone was injured or damaged their property as a result of trying something the read about on here.
As Moe-mentim suggested, alcohol fumes are extremely flammable. When you're heating it (on an ELECTRIC stove or hot plate for God's sake), the fumes can get very thick. If you have the light set up right, you can actually see the shadow that they make.
BE CAREFUL WHEN EVAPORATING iPrOH! I have found this out the hard way before. Once, when doing a half-assed synth of methcathinone from pseudoephedrine, using KMnO4, I was evaporating alcohol from my finished product, on a fucking gas stove, can you believe that? Well, a flash fire resulted. Almost burned my apartment down. I tried to BLOW it out. Not happening! So, I just let it die down. Left a black smudge on the kitchen ceiling that I could never totally get to go away.
A flame does not have to actually touch the alcohol to start a fire! Fumes can travel several feet and will ignite with the smallest tiny little spark, even a lightswitch being tripped could do it, or the switch on an electric heating element might do it too. Just be careful with all that safety shit.
- Carry on, kids.