I made steaks for dinner tonight (they were quite tasty). Despite the warnings in the manual for the grill, and multiple close calls, I forgot to burp my grill before opening it while grilling at 650°.
Since the grill is air tight, the only air that comes in goes into the bottom vent and comes out the top vent, a sudden rush of oxygen will ignite spectacularly. I had my eyes closed so I didn't get to see what the flash looked like, and I've never heard a sound quite like it so I can't describe that either. But it did burn off a bunch of hair on my arm, face and head and I got a very mild burn on my arm.
I may not be able to describe what it looked or sounded like, but I can tell you what it smells like. The burnt hair and skin smell like burn popcorn.
If anyone is looking for effective and efficient hair removal techniques, a flash from a Big Green Egg will do quite nicely.