Leviathan

I was at pizza inn with my friends one night and as I went to drive off the lot my car started smoking and the buzzer alarm thing went off. We popped the hood and it turned out that it was actually the antifreeze that was evaporating out cuz it was so hot. I took a risk and drive it home the next day after pouring water in it with the buzzer still going off and decided to go ahead and just replace the water pump cuz thats what I thought what was wrong, but after replacing it the buzzer still was on, and the steam(or smoke?) was actually coming from underneath the car. It looked like it was coming from some pipes that connect to the catalyctic converter, which really doesnt make any sense at all. We poured water into the radiator and the engine doesnt actually overheat or anything but we still see smoke. My dad thinks its something related to the transmission cuz he saw some of the trans fluid leaking. Anyone ever had any similar problems? Its an 86, automatic, n/a btw.