Wow! I had an old Chevy station wagon which would bleed excess fuel into the exhaust (I think) and would have a delayed backfire about 20 to 30 seconds after I shut it off. Sounded like a shotgun.
Sounded impressive in an enclosed area, like a parking garage.
I had an old Pontiac, did the same. Must have been a GM thing..................
I drove a Chevy ban in 1970 for a Severna Park parts store. The fuel mixture would catch on fire in the carburator. The engine cover, inside the van, had to be removed to put out the fire. Ah, the good ole days.