I am about to cry, sorry for the pipe but a good example of how burnouts look like.
https://www.youtube.com/watch?v=VAEZGYHDtSM
https://www.youtube.com/watch?v=VAEZGYHDtSM
this is what the video uploader says "This what happens if you don't break in a new pipe, You hot pipe it, You clench the crud out of the stem, don't let it rest. Briar is a natural material and you need to break in a new pipe and build a protective layer of carbon. Let them rest and don't smoke 8 bowls a day like a furnace through the same pipe....this is a friend in town. He paid for one, burnt it and I gave him three more that ended the same way. I won't even talk about pipes with him anymore."I think this is probably a flaw in the briar that invited the burnout. The other possibility would be someone who started smoking a pipe but did it in a frenetic way that found an irregularity in the briar that otherwise wouldn't have been a problem, but I'd bet on the flaw that just burnt out with regular use. Few pipe smokers ever see this, but among many thousands of pipes, I'm sure it happens.