Coolant

What is your question?

Ok guys, me again with the Mazda. After changing my thermostat on Thursday I have driven the car about 150 miles on both highway and street. Today, Monday, I saw coolant leaking everywhere. No overheating, hoses seemed to be dry and waterpump too. I poured more coolant in to get me home but it took it as if it was already full. My question is, is there on overflow mechanism that releases when it's too full?