When you match more than 7 bubbles, you create a power-up. Triggering a power-up takes one move. There are 3 different power-ups: 

Rocket: Match 7-10 bubbles to create a Rocket. Once fired, a Rocket clears out a vertical or horizontal line on the board. The direction of the rocket is randomly decided when the power-up is spawned.  

Firecracker: Match 11-14 bubbles to create a Firecracker. Once fired, a Firecracker clears out a small area on the board around the power-up.

Color Beam: Match 15 or more bubbles to create a Color Beam. Once fired, a Color Beam removes all bubbles of the same color from the board. The color will be the same as the bubbles from which the Color Beam was created.