why when you touch bubble with dry things it is popping?

Answer 1

For a bubble to exist, the surface tension of the bubbles surface (interior and exterior surfaces) is in a delicate balance with the liquid sandwiched between the two surfaces. When you touch the surface of a bubble with something dry, it can, though doesn't always, disrupt the surface tension allowing a hole to form. Once a hole forms, the air, which is under a light pressure, rushes out as the surface tension seeks to reduce the surface area or the liquid forming the bubble - collapsing the bubble.