How different concentrations of H2O2 affect enzymes???

Hey,
Recently in school, I did an experiment on how different concentrations of Hydrogen Peroxide (H2O2) affects the rate of an enzyme reaction. I did this by putting liver into different cylinders containing H2O2 @ 10%, 15%, 20%… up to 30%, then I measured the speed of the reaction by measuring (timing) the time it took for the bubbles created on the surface to reach a goal height on the cylinder.

I need to write a lab report on this, and my hypothesis is/was that 'the rate of the reaction got faster as the H2O2 got more concentrated' based on the time it took for the bubbles to rise. However, my hypothesis was completely wrong. As the H2O2 got more concentrated, the rate bubbles got slower. in my conclusion I need to state Why this happened??

I have my thoughts that maybe the more concentrated H2O2 is less reactive to bubbles, what I mean is that it might be like water with no soap, hard to create bubbles ,or that the outer layer of enzymes denatured very quickly creating a sort of protective layer around the rest of the liver??? Or is there a better more scientific explanation to this?