Sometimes titles (and possibly other fields) may contain '' or ''' in the source. In wiki context it means italics (2) or bold (3), so to preserve the original meaning VE should add <nowiki> (or html encoding).
Example for a page with '' in its title: http://www.themarker.com/wallstreet/1.3043194
An egregiously bad version of this reported here: https://www.mediawiki.org/w/index.php?title=Topic:U293el8scpngx7dy&topic_showPostId=u2a8s3c8njqmq358&fromnotif=1#flow-post-u2a8s3c8njqmq358
It does this...