This question has been answered at least a hundred times. The problem is your center of gravity is too far forward and you are not compensating enough pushing with your bars, hence your rear wheel hops. You need to find the right balance on your bike during hard efforts out of the saddle. I find it best to do this by starting with form sprints and working up from there. Put some form sprint work into your schedule 2x/wk. Keep the power down to a reasonable level. Concentrate on body position, keeping yourself stable over the bike, and shifting through the gears. You want to be pedaling in circles with the bike flowing beneath you.