Ressonance
Resonance is repeated constructive interference. It occurs when a force is applied repeatedly at the natural frequency of vibration of an object large, and amplitude oscillations are the result.
Crystal glass wine goblets are especially resonant because of their hollow tubular shape. Therefore if a person sings the same tone as that ringing not the sound of the voice will vibrate the air molecules around the glass at its resonant frequency, causing the glass to start vibrating as well. If it is sung loudly enough, the glass will vibrate itself to smithereens.