Not if the people writing to error messages keep in mind who they are for. "ERROR 574B: ''' not expected" will send most users running for the hills, sure, but "Please put ''' where you want the bold text to finish" should just help people learn.
Imagine if you find this error while editing a long article (say any en.wp country article). Is the error going to be smart enough to locate where the wrong symbols are? The edit box doesn't have line numbers.
It can theoretically be done. Here's an example for the "Bold one / bold two" test: http://can-we-link-it.nickj.org/suggest-links/suggester.php?page=User:Nickj/... (i.e. it prints the start of the line with the problem - but it's still hard to find things in a long article)
For this malformed input: http://en.wikipedia.org/w/index.php?title=User:Nickj/sandbox&action=edit
... but whether something like this should be done or not, and if so how to present it to the user, is debatable.
BTW ''' is valid. ;)
Personally I would include being balanced in the definition of valid, which this example isn't - but it (and all input) is basically valid at the moment, since the parser never complains about anything (well, <math> extension tags can and do complain and generate red errors on bad input, but they're an extension and an exception, which does not affect most people).
I have to agree with David on this issue.
David's point is a good one. We already have technical and social barriers-to-entry, with guidelines, rules, processes, a particular style of doing things (etiquette, social norms, etc), combined with some knowledge of wikitext required to do things. The last thing we want is to make it even harder on new users. So any warnings about malformed input either have to be opt-in, or there needs to be no errors. Either seems fine to me, just don't foist technical warnings or scary-looking red messages onto people who don't want them, or know how to resolve them.
-- All the best, Nick.