Re: Is it true that an ice cube frozen for a period of time will pop in water?

A possible mechanism for "popping" might be as follows: Air bubbles in the ice cube are possibly compressed when the ice is cooled and shrinks (that might need time). The pressure within the bubbles grows and when the ice melts in a glass of water, the bubbles are released and make noise.

[note added by MadSci Admin: Another possible source of the "popping" might be the cracking of the ice cube as it encounters a sudden change in temperature. As to why an older ice cube would make more noise, I don't know. There are previous answers here and here which give some insight about cracking ice.]