Coolant Resvior

Would would cause the rupture of two coolant tanks in a row on a 01 sable?

First, the OEM coolant tank got a crack in it, and coolant started to seep out.

It was replaced with a replacement tank (not oem), and just recently, the coolant inside it began to boil which caused high presure to build inside it, and caused the top of the lid to leak coolant out?

Now, im thinking this is the cause of a bigger problem? If I replace the tank again, would this problem come back again? Why would the coolant inside be boiling, the temperature was not overheating, it was in the middle.

A head gasket blown between the cumbustion chamber and the water jacket.
Is your guage registering accurately?
May not actually be boiling, just air in the system.
Bad radiator cap.

I have no reason to believe that the gauge isn't reading correctly. The car runs fine besides besides this one problem. And it was defintly boiling, as steam came out after I took off the cap.

I am pretty puzzled too. I have a very slow coolant loss from my reservoir and I suspect it has a small crack. Its cap says it runs with 16 psi & "Do Not Remove When Hot" and it almost looks as though the water circulates through it or at least presurerizes it as I see some turbidity or a few bubbles in the lower front section where the larger hose (about 3/4" ID) connects. Seems a strange setup. Car runs fine and heat seems normal. On a cold day I go about 2 miles and when stopped at a light, I see a small amount of steam puff out from the front of the hood and then it seems to settle down.

I had the same problem on my 98. I Replaced the reservoir and cap, flushed the hell out of it and replaced the coolant mixed with this <http://media.doitbest.com/products/571624.gif>; It's worked fine since.