Cataclysmic Variables - Solution

What do you observe?

The air mass from the large balloon was transferred to the smaller balloon, which may have caused a small outburst.

What property of cataclysmic variables is demonstrated in this activity?

The concept being demonstrated here is that with a sudden mass transfer from a white dwarf to a main sequence star, one can detect a change in brightness and a sudden outburst. By studying the outer layers of a white dwarf star, astronomers can learn more about the later stages of stellar evolution.