Not really related to any explicit field of study, but...
Most recently, I was surprised by the extent to which the Japanese still use faxes.
Before that, I was really surprised by the whole Planetary Resources thing. My model of the world claimed that aside for some relatively minor stuff like space tourism and such, plausible pushes to actually do something new and non-trivial in space simply do not happen, and that there would be essentially no real progress in any kind of space exploration before the Singularity. At best, there would be a new private space station in orbit, or NASA would announce a manned Mars mission that would get quietly killed by budget cuts a few years later. Having a bunch of billionaires announce a real effort to actually mine asteroids was something that made it slightly easier for me to alieve in the Singularity happening some day. Before, both asteroid mining and the Singularity used to belong to the mental category of "things that I intellectually acknowledge as possible, but which would be such huge changes to the current paradigm that on a gut level, I don't really grasp either of them happening".
Why it just something which made it easier to "alieve" (in contrast to just believing) in a singularity, or do you think this information was good evidence for updating towards that a singularity is more likely? (eg because it shows that billionaires might invest in such crazy projects)
I recently flipped through the "Cartoon Guide to Physics", expecting an easy-to-understand rehash of ideas I was long familiar with; and that's what I got - right up to the last few pages, where I was presented with a fairly fundamental concept that's been absent from the popular science media I've enjoyed over the years. (Specifically, that the uncertainty principle, when expressed as linking energy and time, explains what electromagnetic fields actually /are/, as the propensity for virtual photons of various strengths to happen.) I find myself happy to try to integrate this new understanding - and at least mildly disturbed that I'd been missing it for so long, and with an increased curiosity about how I might find any other such gaps in my understanding of how the universe works.
So: what's the biggest, or most surprising, or most interesting concept /you/ have learned of, after you'd already gotten a handle on the basics?