I had a Sportsman 48 Remington do something like that out trap shooting at a pit, loaded 3, quickly poped off 2, and on the 3rd... well... I was shooting walmart value pack shells, extractor ripped the low brass totally off the hull, shot exited the action sideways, charging handle went flying, of course thats a removal piece, just clips in and out kind of as a safety, wad exited the muzzle, the hull of the shell was about 6" down the breach.... had to shake the rest of the shot out of the gun.... bolt totally locked back like it should on a last shell though.
I think the entire hull/wad/load tried to exit the barrel and everything but the wad followed the path of least resistance inches from my face
went and bought my benelli later that day after I changed my pants... no injury, no visable damage to gun... havent shot it in 10 years, retired it at that point... still a good looker, never bothered to get it fixed or looked at, only shoots 2 3/4, but ive thought about it...
I attributed it to being grandpas old shotgun, but.... having second thoughts on that call