Why Dump File feature in Soapui 5.2 creates file with unreadable contents?

I'm trying to store the response from a Soap request by using the Dump File property in my TestRequest properties editor. The following is a small excerpt of the output file:

‹  í½`I–%&/mÊ{JõJ×àt¡€`$ؐ@ìÁˆÍæ’ìiG#)«*ÊeVe]f@Ì흼÷Þ{ï½÷Þ{ï½÷º;N'÷ßÿ?\fd
löÎJÚÉž!€ªÈ?~|?"ÿïez™×MQ-?ûhw¼óQš/§Õ¬X^|öѺ=ß>øè÷8ú“ÇM•­./ó²Zå)½´l½kŠÏ>š·íêÑÝ»WWWã«{㪾¸»·³³{÷÷þâùëé<_dÛŲi³å4ÿȾ5»ù-ÓÝÚÖ ÕŒé+|ίᗻ¹âu÷#‹ê“jv?Nê|V´'ó|úöUÞ¬ªeã°<¾ÖPƒ7Š²$§Õbœ­

The request is a step within a test case. The encoding is set to UTF8. I opened the file using Notepad++ and tried to play around with different encoding but got no luck.

Any idea?