I have a 2010 Toyota Venza 3.5 V6 AWD with 103k miles on it. Just bought it about a month ago, been a fantastic car. Yesterday while heading to our Thanksgiving destination it broke down with the family in it. While climbing a hill we heard the belt squealing just a little bit, couple seconds at a time. Then it went away. Next thing I know the master warning light came on and said the coolant was too hot, temp gauge was about 3/4 of the way up.. Immediately pulled over and shut it off. The belt was still on there, there was some coolant that got sprayed around a bit. Coolant hoses didn't appear to have any holes or cracks in them. 

I had my wife start it up and it was making a rattling sound where the pulleys are. My guess is the water pump took a dump on us. Any other guesses out there? $154 tow bill so far. Should I take the belt off tonight and try moving the pulleys around to confirm? Thanks for the advice guys.