Had a very interesting situation today on my first trip on the beach. After about a 40 min highway trip to get to the beach I locked my differential and drove another 10 minutes on the sand to get to my favorite fishing spot. I looked at the temp gauge and it was into the red. I never witnessed the temp this high before and have driven extensivly on the beaches of the south shore of Long Island. I immediately stopped and tuned off the engine. Opened the hood and found the coolant overflow tank making a boiling noise. I let the engine cool down and looked again and noticed that all of the hoses seemed to be “sucked” almost flat, the upper and lower hoses along with the hose that goes from what I believe is the water pump. I opened the radiator cap and air was sucked in and the hoses expaned to normal. I added a quart of water to the radiator to fill it and drove the truck all the way home with no abnormal temp reading. I was planning doing a coolant flush for some time but have been remiss. The truck has 79,000 miles on it, any ideas of what happened today.