582 gray head rotax

The question I have concerns a Rotax 582 Gray Head.  The engine runs fine and has 25 hours on it.  During the last flight when the throttle was  retarded the antifreeze solution began to spit out of the tube that is located just in front of the radiator on the right side of the airplane.  It has never done this before.  All the engine temps, CHT's were normal.

Now when the engine is warmed up on the ground all that has to be done is increase the RPM'S for a short time and when the throttle is reduced to idle the water exits the tube in front of the radiator.

Any suggestions as to what is going on with the engine??