This effect creates vertical streams of bubbles based on the original image which you have imported.
As usual, the best way to see the possibilities of a single effect is to hit F8 or the (dice being ticked by a feather) icon in the toolbar..
With F9 (or the slider icon in the toolbar) you can change the settings of the bubble effect. The settings are:
|•||The total number of bubbles in the image|
|•||The average bubble size as a % of the x dimension of the image|
|•||The foreground color of bubble outlines|
|•||The highlight color on the bubbles, and from where the light is coming from which forms the highlight|