MAMP 2.2 uses OPCache to cache PHP scripts. So if you make a change to your PHP script, and execute the script in the browser, you will not see your change right away. Looking at the OPCache configuration in MAMP (as defined in php.ini), the cache timeout interval is set to 60 secs. So it caches for every 60 secs and reload the scripts. This can be issue for development since you would have to wait that long to test and see your changes. This caching can be turned off by modifying the OPcache interval for re-validation.
This parameter is defined in the php.ini file that comes with MAMP and is located at
Open this file in vi or any text editor and search for opcache.revalidate_freq and you would see that it is set to 60 as show below:
Now change that parameter to 0 as opcache.revalidate_freq=0
Save the file and restart MAMP and now you should be able to see your PHP script changes right away every time, no more caching.