want to download 3GB database table from my development mysql server
The simple answer is "use the command line tools", these will run until complete assuming you have enough disk space, to produce the backup then draw that down to where you want it (if not the same server) via HTPS, SFTP, or similar. 

The other option of course, unless you need up-to-the-minute data, is to take a copy of the latest backup. If you don't have regular backups already then look into implementing them otherwise you are setting yourself up for a potential world of hurt later.

For more detailed/specific answer you'll need to update your question to describe you environment and what you have tried so far in more detail. Is this your own server or VM, a work machine you have limited access to, a shared host, ...? Linux/Windows/other? What actually happened on your attempts other than "didn't work"? A long delay then nothing, a long delay then an error message, an error message quickly, a fire is produced but is empty or incomplete, ...? If an error message: what was the text of that message?