Saab "blow up"

I have a 94 saab 900 turbo manual transmission. I had been driving around in the heat today, had it idling for awhile then started back up. I was going about 15 mph when I heard something explode somewhere in the car, then smoke (not steam) streaming into the passenger compartment. I was able to stop immediatly. Engine did not die. Passersby asked if I was OK; they could hear the explosion from down the street, saw the smoke, and thought I might be injured. Car quit smoking immediately, lingering smell was not sweet coolant smell but burning metallic and rubber smell. Towed car to auto shop, where they could find nothing wrong. I have not yet found out exactly what it was that they checked. Any help would be appreciated, especially if anyone has had an experience like this. I plan to leave the car at the shop until they figure out what happened or have it towed to another shop.

Could be a backfire. Check the air filter, both sides for evidence.

I agree it could have been an intake backfire but can’t guess much more than that.
The engine continued to run. Run badly, normal, any lights illuminated on the dash?
Towed because it was running badly or would just not move?
Just wondering if an alternator could have gone up in smoke.

I’ve had locked up AC compressors generate an impressive amount of smoke too, but without the bang. How about a burst AC hose?

Please let us know when you find out.

Thanks for your ideas. The car ran fine after the “blowup” – no lights on dash. I had it towned because, quite frankly, I was afraid to drive it. I didn’t know if it would start on fire or I would blow the engine etc. etc. My mechanic has checked all belts, hoses, fluid levels. He drove the car and said it ran beautifully – ruled out a backfire. He’s going to put it on the lift today and check underneath and drive it around a bit more. I’ll make sure he checks the AC compressor.