Check the sprocket by spinning the wheel and holding a pencil, screwdriver, stick, whatever, right above the teeth. As it spins, check the gap between the teeth and the stick.
You'll notice if it hops up and down.
But that wouldn't make your wheel hop. It'll just mess with your chain tension. And they all have a little bit of out of round-ness.
It's the wheel or tire that would make it hop. Or a severely bent axle.