Mythbusters used 10W NIR and foil if I remember correctly. Someone here did it with a blue. He spun the kernel on a motor. (edit: see link above) I've done it with foil and a CO2 laser myself. It needs to be heated evenly and slowly, or you just end up burning it.
LOL, this is funny I was bored and did tried this last night with my 2W 445nm. I knew about the even heating but I was lazy and just hit the thing with an unfocused beam. Well, it went up in smoke in less than 2 seconds and my room smelled like burnt popcorn for the rest of the night XD
Next time around I'm going to drop it on top of a very slowly rotating computer fan in foil and see if I can get the sucker to pop
What you should do it put a little bit of oil engulfing the kernel/s and heat the oil not the kernel/s. then it might actually pop and have flavor. Just be cautious of flung boiling oil! That shit hurts!