Hi,
There is actually no products listing with a popup to open a product details page in HikaShop.
So that means it's a modification that was added on your end and thus I don't know how to revert it to have it work like it does by default and how you want it.
However, it's likely that the modification was made with a view override. So check the folder templates/YOUR_TEMPLATE/html/com_hikashop/product/ via FTP.
You'll probably find a listing_img_title.php file. In that case, rename it to deactivate the view override and it should work like you want.
If you dont' find that view file or the renaming doesn't change anything, it means that it's probably another view override in the same folder so try to rename the other files there one by one to identify the culprit.