200 grand prix pop from engine area. Please help.

[justinmoline]

Have a 2000 3.8 Grand Prix with about 70,000 miles on it. Having a off and on probelm with it seems that when the car has been driven for a while and warm/hot and you go to a gas station or some sort of stop and you go back to start the car there is a somewhat load POP that comes from the engine area. It does not do it all the time, but it usally always seems to to it while it hot and once you start it back up fairly soon. Any one else had this problem any suggestions. Justin