for my gallery I have used a typical button filled with picture an text.
When you mouse over a banner appears indicating name of project
before you click to go on that target project.
at screen 320 I have used text size 8 for the above banner
at screen 1500 I have used text size 14.
When I test from 320 to 1500, text size 8 goes on the banner @ 1500
and when I test from 1500 to 320 text size 14 goes on the banner @ 320.
Furthermore, pictures within the buttons also reflect such behaviour
by expanding and contracting, and loosing their positions.
I would really appreciate if someone would know.
Please share the link to your site so we can have a look at it?
Do you see this while resizing the browser window?
How does it work in actual devices? Try using responsive simulators inbuilt in browsers.