title: vagrant virtualbox disk grows in size for no reason
body: <p>I'm using a vagrant with virtualbox for my development environment but the disk size grows in size for no reason. When I first create the box and provision it, the disk size is about 4GB but after 3 months of use, the disk size is about 18GB even I didn't install anything new all that time. I just can't explain what takes all those gigs. </p>
  
  <p>Any idea why this happens or any solution? Having multiple boxes just eats up a lot of my disk space for no reason.</p>
  
  <p>Thanks!</p>