Sonoluminescence is the emission of light from imploding bubbles in a liquid when excited by sound.
Single-bubble sonoluminescence – a single, cavitating bubble
Long exposure image of MBSL created by a high-intensity ultrasonic horn immersed in a beaker of liquid
A bubble is a globule of a gas substance in a liquid. In the opposite case, a globule of a liquid in a gas, is called a drop.
Due to the Marangoni effect, bubbles may remain intact when they reach the surface of the immersive substance.
Air bubbles rising from a scuba diver in water
A soap bubble floating in the air
Bubbles of gas rising in a soft drink