Two recent planned breakthroughs: Einstein's theory of general relativity predicted the existence of gravitational waves, and LIGO detected them in 2016. Bell predicted that entangled quantum particles would exhibit fundamentally nonlocal properties, and in 2015 the first "loophole-free" test demonstrating violation of local realism occurred.

These experiments were done with expectations of a result. That is not to say that they had foregone conclusions, just that there was some phenomenon that the scientists hoped to see, and confirmation one way or the other would be of interest to the community. Most experiments are like this -- of course scientists should keep their eyes open for unexpected discoveries, but in general pursuing expected results is more fruitful.