You can do it by using explode()
function:
$string = 'http://domain.com/106.jpg,http://domain.com/109.jpg,http://domain.com/112.jpg';
$split = explode ( ',', $string );
It will return an array. So you can print this way:
echo $split[0]; //will print http://domain.com/106.jpg
echo $split[1]; //will print http://domain.com/109.jpg
//and so on