It is really weird and I can't verify it but I swear my bike wants to wheelie when in second gear and leaning over if I crank it. (ie a city street corner.) I have noticed this a few times but can't reproduce it on demand. Maybe it is something in the shape of the road surface that causes the wheel to jump up or maybe it is my imagination, I don't know.
Also don't discount the force of your front springs. When you are leaned over your front springs are somewhat compressed from the centrifugal force. You get on the throttle and it unloads those springs, but since they're compressed already you get extra upward force.
You can see this effect on bikes and on cars. Cars sliding in a full 360 degree turn will compress the outside springs, then as they rotate beyond 180 degrees, those springs release that energy and often times the car will simply flip over onto its roof when that energy release combines with the sideways force that is now on the opposite side of the car.
Be particularly careful if you are in an accident avoidance maneuver (swerve), as you get fast compression and de-compression. Say a car pulls out of a side street in front of you, then sees you and stops right in front of you. If you quickly swerve to miss the car, you can really compress your front springs, and if you get on the throttle as they are de-compressing you can easily loft that front wheel without meaning to.
Another scenario to be cautious of is if you start to make a left turn, see an oncoming car, hit the brakes, realize you're already too far into their lane and decide to go for the turn in front of the car. Having hit the brakes, your front end can be almost fully compressed. Then you change your mind, release the brake, hit the throttle, and you will find yourself wheelieing across that road, surprising that driver and yourself.
It's good to practice that though, in a parking lot. Hit the brakes to compress your front end, and hit the throttle as you release. It takes very little power to loft your front wheel when your front springs are rebounding at the same time.