My car began to overheat suddenly. Then I heard a loud but muffled pop, the car stopped, steam started coming out but it seemed to me that though I turned the engine off it continued to try to run for a minute or so. While it was overheating I smelled no coolant or steam from the radiator, the car itself kept running well, that is to say, there was no discernible reduction in power from the engine. Until the muffled pop sound. Can you explain to me what happened and what I should do please?