If you don't mind messy markup, you might try a span with
whitespace: nowrap
but then it might drop down to the next line, leaving a ragged right margin.
You can experiment with other whitespace settings, and see if any give a workable result.
http://www.w3schools.com/cssref/pr_text_white-space.asp
I keep seeing breaks with nbsp and with trailing emdash all the time. I often even see a break between a full stop and the closing quote mark --- kerning and hyphenation algorithms leave so much to be desired!
