Boiling coolant in reservoir car not overheating

I own a 2003 Mazda money-pit (protege) we have done ALOT to it. Radiator blew so we replaced radiator, hoses and reservoir.car kept overheating, so we Changed head gasket and thermostat. New plugs and wires and harness. Car is running smooth no overheating no missfire now but the coolant is boiling after driving. Is this normal?