"Fire in the Hole!!!"
This is what the guy who created this ingenious smoke-ring blower (seen in purple just to the right of the flame trailor) yells just before chosen spectactor(s) (seen on the far right of the left frame) pulls the cord to release this mega flame. This flame then shoots up the biggest smoke ring I have ever seen (right frame) - must be about 50 feet in diameter at it's peak, and can be seen from anywhere on the playa (the whole Burning Man grounds).
The frame on the right was taken at a different point - he was shooting these off about every 20 minutes every day all day long. Damn impressive.
Playa aerial photo here from 2005.