You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <alltransclusions gatcontinue="Bossinfo|31" />
  </query-continue>
  <query>
    <pages>
      <page pageid="7" ns="0" title="Aet&#039;Thol" />
      <page pageid="8" ns="0" title="Blue Dragon" />
      <page pageid="23" ns="0" title="Atrium Monarch" />
      <page pageid="24" ns="0" title="Demonic General" />
      <page pageid="25" ns="0" title="Banshee" />
      <page pageid="26" ns="0" title="Spider King" />
      <page pageid="27" ns="0" title="Hedge Lord" />
      <page pageid="28" ns="0" title="Giant Sand Wurm" />
      <page pageid="29" ns="0" title="Lyzanthir the Enchanter" />
      <page pageid="30" ns="0" title="Crystal Giant" />
    </pages>
  </query>
</api>