serbing overheating

2001 ch serbing overheated and blew a freeze plug. The freeze plug was replaced, along with the water pump, timing belt, and thermostat. The car sit and idle for about 30 minutes and is fine. Drove the car the other day for about 25 miles and fine. Pulled back up in the drive way opened the hood, and the top hose from the cap to the raditor is real hard and water starts spraying out of the raditor cap, then the temp starts going up on the car. Any ideas on what could be causing this? Anything else to be checked or replaced?
I really like the car and would love to get it running safely again with no worries.

thanks for any help