Subject: Why would a glass of pepsi spin smoothly on ceramic and not water?

At Christmas dinner we discovered that our crystal glasses(which had a 
slightly rounded bottom) filled with carbonated drinks spun smoothly on 
the ceramic coasters and the glasses with water did not. We tried 
variations: with and without ice for both, different glasses on different 
coasters, different levels of liquid in each and even checked for 
condensation. In all instances the pepsi spun smoothly and the water did 
not. My curiousity will not let me sleep. Please help.

Re: Why would a glass of pepsi spin smoothly on ceramic and not water?