China Miéville - The City & the City is one that I don't think I'll ever forget. Wild because as far out as it feels, it's also a pretty accurate portrayal of how we've trained ourselves to intentionally not see. I find myself thinking of the book often.
The premise for this book was so strange I often had to reread passages to fully understand the differing perspectives of people standing next to one another and yet be in two different realities.