89 cavalier massive coolant leak

[HeWhoKillz]

I have an 89 cavalier with the 2.8 engine. This car is really just the car that sits around at home until someones main driver dies or has to be fixed. It really doesn't go out of town much but it really hasnt shown any issues with out of town driving. Today I drove it on the highway for about a 60-70 mile trip. I actually made a stop to get my girlfriend about half way and the car was fine. When I got to my destination, I turned the car off and we began to hear a noise that sounded like someone had pushed the release valve on their air compressor. Now this also happened two years ago when it went on another highway trip that couldn't have been much more or less than this one. I knew exactly what was happening with needing to get out. All of the coolant began to purge out. I know it comes from the front passenger side. I never saw any issue with the heat gauge. When this happened two years ago, we put water in it and took it to a shop that said a hose came off? Whatever, so they clamped this hose back on and never had an issue from the car again. I don't see how this could be. We put some more antifreeze in the radiator once it was cool since I had some in the trunk. The gauge was not overheating so we drove the car home. When we got home, nothing happened like this. The only thing that seems to be the same from this time and last time is that it was after a long drive and after the car was shut off. If a hose has slipped, wouldn't I be losing coolant while it runs? I know my gauge works because after all the coolant leaked out, I know the engine would be pretty hot. I turned all the electrical stuff on with the key and the gauge showed the pin all the way to the hot end. Possibly the thermostat not working all the time?