You seem to be interested in only a certain output by popping the array you have created. What if you want the array @splitdata to be intact? or that your expected output WAS not the last element for you to be able to access it using pop() the way you did? and what if you did not want to split the $data into array elements?

#!/usr/local/bin/perl
use strict;
use warnings;


my $data = 'Sending 104 bytes ***
POST /path HTTP/1.0^M
Content-type: text/xml^M
Content-length: 37^M
^M
SENT 104 HEADER
HTTP/1.1 401 Unauthorised^M
Connection: Close^M
Content-Length: 0^M
^M
<?xml version="1.0" encoding="UTF-8"?>
<?path?>
';

#(Update) more like the output you requested
print "Last Value=> ";
while(){
        (my $text = ($data=~ /(<\?.*\?>)/gi))? print qq('$1'\n) : exit
+;
        }

#OUTPUT:
#Last Value=> '<?xml version="1.0" encoding="UTF-8"?>'
#'<?path?>'
[download]

the guys on Linux, try it too, I bet it can work fine in there as well....