Pressure release

When I was sitting in idle, my Dodge Ram made a loud popping noise yesterday from under the hood. It sounded like a pressure release. When I inspected it there was one of the hoses that came from, I'm figuring, the return from the heater core was popped off. I pushed them back together and drove on. Thinking that since I just had my whole coolant system replaced, radiator and heater core, there was too much anti-freeze in the system and was idleing too long.
Do you have any idea?