Before you swear off hitting those high notes, hear this: It's unlikely your pipes are powerful enough to break any windows.
However, the laws of physics maintain that a human singer — sounding at the right frequency and with proper amplification — can shatter glass.
All objects posses what is known as a natural frequency, or a frequency at which that object vibrates. If you tap a fork against a wineglass, the tinkering sound it produces is its natural frequency.
A human voice producing that same natural frequency will also cause the glass to vibrate. This common phenomenon is known as resonance and occurs because the singer's voice displaces nearby air particles, which crash into the glass like invisible waves.
And when the singer's voice is amplified, these waves get more powerful. With enough amplification, the glass can vibrate so strongly that it shatters.
Of course, in order to get such dramatic results, the conditions have to be just right. It's easier for a singer to shatter glass if it is very thin, for example. And if a wineglass already has a few tiny fractures, there's a much better chance it will vibrate itself to smithereens.
The effect of a singer's voice on glass has been demonstrated at least once: In 2005, rock singer Jamie Vendera was recruited by the Discovery Channel program "Mythbusters" to test his powerful voice. It took several tries, but he was eventually able to shatter a wineglass with his unamplified singing.