Our web pages our built using client-side AJAX and the URL doesn't change, thus the standard analytics-type libraries which send events automatically based on URL changes etc., those are going to miss the majority of what's going on with the user.
Given a link like:
<a id="loadAjaxContent" href="#getSome">Get it</a>
Listen for clicks like:
Obviously you will want to use classes or some other kind of grouping for simplicity.
Or you could listen for any hashchange:
Take note that if you use standard <a> tags and your hrefs do not start with hashes, then Munchkin will already be attached to them, so you definitely do not want to attach again.
Your question is actually overbroad because you have not specified how your single-page site actually works. There's no one way to use Ajax for content replacement.