There are legions of scientists all over the world, each testing dozens of hypotheses. In at least some of those cases, the data are bound to look funny purely by chance even when there's no effect there. In fact, if that never occurred, that would be the most incredible coincidence of all.
Basically Anything About How Memory Physically Works
One of the jobs your brain does aside from replaying your most embarrassing moments when you're trying to fall asleep is processing information. It takes in information from the senses, it manipulates that information in various ways, and then it stores some of that information for use later. It may surprise you to know, then, that we have basically zero idea how this works. I say, "basically zero idea" because the situation is actually a bit worse than that: we have a bad idea that keeps leading us astray.
Some of the earliest and most influential work on memory and learning was Pavlov's dog experiments. Fans of Cracked will remember his groundbreaking work proving that if you cut a bunch of holes in dogs they will die. But to the layperson he's better known for showing that you can gradually connect two unrelated things in the brain -- say, hearing a bell ringing and salivating as though it's meal time, or hearing Nerf Herder and feeling like your teenage problems are about to be allegorically explained by the slaying of demons.
The better part of a century later, researchers discovered a process by which the brain rewires itself called long-term potentiation. Basically, if you have two connected neurons, one triggering the other over and over, they actually grow closer together. That means over time it becomes even easier for one neuron firing to kick off the other.
"Quit settin' me off, bro!"
Two basically unrelated entities that, when activated in quick succession, slowly forge a causal relationship? Not only is that a great idea for a buddy movie starring two neurons, it's clearly the explanation for how learning works on a cellular level. That's why it's been neuroscience's basic understanding of how memory and learning work for half a century now. And since so much of understanding the brain also entails understanding memory and learning, that must mean this must be bedrock scientific knowledge, right?