I've got a big Harman Oakwood stove. I like the stove a lot... it has a bypass damper and burns pretty clean.

I had a good fire going in it tonight, and I let it burn down to coals before I noticed. I rebuilt the fire with some Juniper and Pinon, got it going pretty quickly, and dropped the bypass damper and turned down the air intake damper.

20 minutes later, my wife came out of the back room and said "the stove is making funny noises"

I went in, thinking it was just settling from the temperature, and watched it for a minute. As I was watching it, I heard a "WHUMP" and a puff of smoke / ash came out of the junction between the stove and the pipe. Holy crap.

Doing some looking online, it appears that the stove can get into a mode where the wood outputs too much gas for the air coming in, and you can get combustion in the stove pipe itself.

I'm more than a little spooked, as previously i have built up a big fire, loaded it with wood, closed down both dampers and have gone to bed.

Not sure I fully know what happened, as this is the first time we have witnessed it. I suspect it was because I had lots of coals making gas and not enough draw pulling in air. I bet that if I don't fill it full with wood on a coal base and crank down the dampers I should be okay. Think I'll talk with a stove shop tomorrow.