$GLOBALS is a special variable. It is used to access global variables, like $GLOBALS["global_var"] but it 
cannot be used for anything else. You can't directly reference $GLOBALS, that is you can't do $a =$GLOBALS
 (the result will be false, which happens to be the empty string and thus you got a string type). 
Note that you can destroy $GLOBALS. If you do $GLOBALS=1, $GLOBALS will start acting like a regular 
local variable in the specific functions life time.