This reaction comes about from what is known as the pinacol rearrangement (at least, this is what my organic prof. refered to it as). The acid will protonate a hydroxide group to form water. The water will leave to form a carbocation. The carbocation will rearrange via a 1,2-methyl shift to form a secondary carbocation connected to the other hydroxide. This rearrangement is favored because of resonance-stabilization; the lone pair on the oxygen can donate electron density to the empty p-orbital of the carbocation, and in general, resonance-stabilized secondary carbocations are more stable than tertiary carbocations with no resonance-stabilization. Subsequent deprotonation of the oxygen results in the formation of 3,3-dimethyl-2-butanone (pinacolone[?]).