title: Split a string on every third instance of character
body: <p>How can I explode a string on every third semicolon (;)?</p>
  <p>example data:</p>
  <pre><code>$string = 'piece1;piece2;piece3;piece4;piece5;piece6;piece7;piece8;';
  </code></pre>
  <p>Desired output:</p>
  <pre><code>$output[0] = 'piece1;piece2:piece3;'
  
  $output[1] = 'piece4;piece5;piece6;'
  
  $output[2] = 'piece7;piece8;'
  </code></pre>