When I open a local file in Kate that is located somewhere outside of my home directory and then click the "Open" button to open a second file, the directory of the currently open file is used in the file picker dialog. 

For example, open /home/user/Desktop/folder/file.txt and when you click on "Open" again, the file picker displays /home/user/Desktop/folder/. This makes opening several files from the same directory very convenient.

This was also the behaviour for previous versions of kate, but after upgrading from Ubuntu 16.10 to 17.04, that is no longer the case for remote files. When opening subsequent remote files, the directory in the file picker is reset every time back to the user's home directory.

Note: I have tested using SFTP, but not any other remote protocol since I don't have any others available.