Don't Believe The Temp Gauge

So I was going down the road and I start hearing a "tapping" noise coming from the engine. I didn't think to much about it because I was going up a steady grade, all the gauges looked fine and the engine had knocked before while going up hill. In a matter of 2 or three seconds, the knocking increased in volume and then the motor cut out. I pulled off to the side opened up the hood and saw that the cylinder heads were smok'in. As it turns out, the water pump had started to go out and could not supply enough pressure to deliver water to the heads. I did not see the increase in the temp gauge before this happened. As it turns out, the heads got so hot that they are warped beyond repair.
The moral of the story is: You cannot always believe in the gauges. If you have any suspicions, pull over and look it over. If not, you may be paying 1600.00 to fix your car, like I am having to.