My kid got a little round box of soapy solution at the fairground with a wire loop to blow bubbles with. She was pretty excited with it for few minutes, then lost interest. Kept it on her desk when she got back home.

The next morning, she tried to blow some more bubbles with it, but the soapy solution appeared to be as dead as plain water, i.e. zero bubbles came out when she tried with the wire loop.

What kills the “bubbleness” of soapy solution over time ? The concentration of the remaining solution should’ve remained the same since the box was closed shut overnight.