Answer
The membrane expands on exertion of pressure and breaks away.
Work Step by Step
Step 1 of 2
When the test tube is taken from the closed fume chamber closed tightly with the cork, there is a constant temperature of the system. When one pushes a syringe, the air gets inserted into the container, this increases the pressure as stated by the Boyle’s law. Thus, the membrane is expected to expand into the test tube so as to balance exerted pressure.
Step 2 of 2
When we keep fixed the syringe, there is maintenance of constant pressure on the membrane. After expanding, the layer gives way and breaks.