I think a bunch of grease/crud buildup on the cylinder head got hot enough to flame up.
I have a Schlitz:
It's got vinyl siding on most of it now, and the overhead door on the end is now held open by a 2x4. It's chock full of worthless junk that I should truck to the dump. There's no room to work.
Anyway, now I'm pretty sure I have to buy parts, but where would I buy Walbro carburetor parts on Memorial Day?