Niels
In the version of Mendix you are using, anytime you place an image widget on a page, you can have an on click microflow. Should be straightforward to build a microflow that would take a Mendix object with a blog post url and display that blog post in a pop up window or, with an add on from the app store, redirect to the original blog page.
Mike
Niels, regarding the microflow timer + url redirector in a popup combination, try these settings in the microflow timer:
Interval: 0
Execute once: yes
Start at once: yes
Did the trick for me in another project.