I tested php sessions with this feature
session_start(); $_SESSION['test'][] = time(); header('Content-type: text/plain'); print_r($_SESSION);
In theory, it should return another element of the array every time I reload the page. But in my case, for some reason, it always displays a single element.
So I'm stuck, please help!
UPDATED
The PHP version on my server is 5.3.13. Here is what I have in the session section. 
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