How do I come up with a "thesisy" thesis title?
You may not actually want your thesis title to sound "thesisy" - many academic manuscripts have ambiguous, wordy, or borderline nonsensical titles. That being said, a thesis is generally the result of substantial work, so the title should reflect that, right? 

One way to do that is to identify exactly what is unique about the efforts. If it ends up on someone's bookshelf (or, more realistically, listed in digital format) then a title clearly stating what is novel about the work it represents will help to distinguish that document. 

It should also be as short as reasonably possible while still being direct - does the thesis have a single, major conclusion? If it's more ambiguous, can multiple conclusions be summarized into one? It may help to phrase the conclusion as an action, e.g. "X does something to Y" or "X shows that Y is Z" rather than "On the nature of X: an exploration of the Y of X using the Z method". Avoiding jargon is also ideal, though standards may vary by field.

Your institution likely has a dedicated collection of previous theses. They may not all provide great examples of titles, but they're worth learning from.