bubbling

Concise Oxford English Dictionary © 2008 Oxford University Press:
bubble/ˈbʌbl/

▶noun

• 1 a thin sphere of liquid enclosing air or another gas.

  ■ an air- or gas-filled spherical cavity in a liquid or a solidified liquid such as glass.

• 2 a transparent domed cover or enclosure.

▶verb

• 1 (of a liquid) be agitated by rising bubbles of air or gas.

• 2 (bubble with) be filled with (an irrepressible positive feeling).

• 3 (bubble up) (of a feeling) intensify to the point of being expressed.

– origin ME: partly imitative, partly an alt. of burble.