Unfortunately code reviews don't ensure this. Reviewers, when faced with code in a domain they don't understand, don't go out of their way to learn it; instead they just look for surface-level / nitpicky stuff.
That's not a problem with code reviews; it's a problem with your company's implementation. "Please explain this" should be considered a very reasonable response to a code change the reviewer doesn't understand. In my experience, this ends in the code being cleaned up with readability in mind and the reviewer learning something new in more or less equal proportions.