Is Polyurethane heat resistant?

I recently purchased an older home that has had little to no updating done in the bathrooms, and I am getting ready to re-do the kitchen and bathroom counter tops. I have found a method that consist of putting a special "wall" paper over the counters and covering them with 4-5 layers of polyurethane. I haven't had a whole lot of experience with polyurethane and I am just wondering if it is heat resistant, because it seems to me like it would melt if it got too hot, say for instance if you accidentally sat a hot pot on it or something. Or from the crock pot sitting on the counter all day? Just wondering. Thanks