Q: What could the problem be?

I pulled out of my drive way, drove maybe a quarter mile. Suddenly I hear the alternator belt squeal. Then my battery light came on and either the power steering went out or the steering locked up. I managed to pull over barely. Then I tried turning around to head back home. It took 8 to 10 tries backing up and pulling out because the steering wheel was so hard to turn. Everything else was working just fine. I eventually got it back home and raised the hood. Antifreeze had sprayed all over that side of the car. I checked the coolant tank and it seemed low. I decided to fill the tank back up. I started it and there was no spraying or leaking and after it dried out it drove just fine. I did notice that the coolant tank cap didn't seem to be down all the way. It's one of those pop caps without threads. If it was loosened by a bump or something could it cause the tank to spray or splash? I've never seen that happen before. Any ideas will be greatly appreciated.

My car has 135000 miles.
My car has an automatic transmission.