I liked the question but also recognise the difficulties in testing it. Firstly all sponges are different so to make the testing experiment fair you would have to use the same sponge. You would need to dry it in between the tests. I think a microwave could help with that.
You then have to think about the water. If you put the hot sponge into a bucket of cold water it would very quickly cool down so the temperature of the water should be about the same as temperature of the sponge BUT water expands on heating so maybe the sponge will not be able to absorb as much water because of the expansion. Finding out how much water is absorbed can be done by squeezing the water out into a measuring cylinder BUT how can you be sure that all the water has been squeezed out.
So we have an idea (a hypothesis) but we need to think more about how we can test that idea. Have you got any further ideas Isabelli? If so you could leave a comment.