I was more after some discontinuity than a simple nonlinearity, like a quadratic or even an exponential dependence. And you are right, the selection effect is at work, but it's not a negative in this case. We want to select similar phenomena and find a common model for them, in order to be able to classify new phenomena as potentially leading to the same effects.

For example, if you look at some new hypothetical government policy which legislates indexing the minimum savings account rate to, say, inflation, you should be able to tell whether after a sizable chunk of people shift their savings to this guaranteed investment, the inflation rate will suddenly skyrocket (it happened before in some countries).

Or if you connect billions of computers together, whether it will give rise to a hive mind which takes over the world (it has not happened, despite some dire predictions, mostly in fictional scenarios).

Another example: if you trying to "level up", what factors would hasten this process, so you don't have to spend 10k hours mastering something, but only, say, 1000.

If you pay attention to this leveling effect happening in various disparate areas, you might get your clues from something like stellar formation, where increasing metallicity significantly decreases the mass required for a star to form (a dust cloud "leveling up").

Classifying, modeling and constructing successful predictions for this "quantity to quality conversion" would be a great example of useful applied philosophy.