Sudden crackling after 2 miles

I just got home after driving only two miles and when I turned my K5 blazer off I heard loud crackling underneath the front end mostly like something is really hot maybe. I thought it was gonna explode. My oil gage seems to move towards being really full also but no warning lights have come on. I had read other posts about the cat but this was a short drive and does not seem to match the other stories for this reason. I read something about fuel too, I just had the fuel pump replaced a week ago and when I turn the vehicle off now I hear something quietly thud near the back end. I am afraid to start or drive it after this crackling experience tonight. I have another issue worthy of another thread which I will post next. Help please.:frown: