Webserver doesn't show actual file

I have an annoying problem with a webserver, btw. I don't even know if it is him.

I upload a test.php with simply

echo "asdasdasdasd"; 

in it .. i call it with the browser and then update the test.php to

echo "qqq";

.. then I press F5 .. but the server still shows the output of the old test.php. When I wait 3-5 min and press F5 then, the actual test.php is shown.

I tried with different browsers and with cache completely disabled, but still the same effect. I have never seen something like that before, can someone help me? It is very annoying to have to wait for every "refresh."