Definitely not like a steam pot. It sounded as if the center vent vacuum actuator was having a fit. How low does the coolant have to be before the light goes on. The light was the last thing to go on just as I was to turn off the car, by that time the noise was long gone and the temp had begun to drop. I opened up the hood 10 seconds after stopping the car, no steam and everything was bone dry except for a VERY small amount of liquid around the expansion. Not enough to even drip anywhere. As I mentioned, I added 1 liter of water and now the water level in the expansion tank is higher than what is was before. Before: a little less than half full in the exp tank, now almost completely full. By the way, oil is clean as is the coolant. No mixing of the 2. Thankfully, engine problems seems to be out of the equation at this point.

By the way, Manny, the other post was very interesting but the guy who described the duo valve is pointing me to a water pump impeller failure. The duo valve blocking coolant flow (if that's possible) seems like a logical explanation given what I've experienced. Any disagreements/comments are welcome.