Heddon Tiny Torpedo
Fishing with topwater lures can offer explosive action and big fun, no doubt about it. Bass will attack that twitching bit of plastic, hitting the lure like steam train before pulling it down into the depths, and the fight’s on. 
The emphasis here is on can; a lot of the time, if you’re me, poppers, torpedoes, spooks and the like produce no action at all. Still, the other day at Lake Whitney I had good success with a Torpedo and decided to read up on the subject. I found this article helpful, here’s an excerpt:
Wham! When the strike came, I stifled my jerk reflex and waited for the fish to pull the bait down. Then, when I felt tension, I set back, and in short order a surprised three-pounder was flopping in my net.
Heddon Spook

…Most every brushpile harbored bass, and my Tiny Torpedo and that stay-put, irritating retrieve were the keys to catching them. Those fish never hit when the lure first gurgled into range. Instead, it was the twitching that changed their mood from neutral to aggressive. By tantalizing them long enough, the lure triggered their instinct to kill the “helpless prey” even though they weren’t hungry.
So this is the object with topwater lures, to present bass with a vulnerable, unaware “creature” that is an easy target, then allowing nature to take its course.

You can read the rest of it here and learn something about the why, where, when and how of topwater lures. For me the why’s simple, sheer excitement at the ferocious, leaping, impact of the Bass. 
Lake Aquilla, The Challenge Is On!
Nothing like it and while I’m no expert, the success I have had makes me want more. A lot more.
Fish On,