How to update a single cell in GridView without refreshing the whole page ?

Hi,

I am displaying information in a GridView . 
The data is in a static class called Data (will be replaced by a database in future).
To upload the information to the GridView , I am using a DataTable like so:

    public partial class WebForm1 : System.Web.UI.Page
    {

        private DataTable dt;
...

        private void BindGrid()
        {
    
            dt = new DataTable();
// Here we populate the DataTable with information from the "Data" class 
...

            dt.AcceptChanges();
            GridView1.DataSource = dt;
            GridView1.DataBind();
        }
   }

When a cell in the GridView is clicked, a user gets a popup form , edits the content and the cell is updated (there is text, background color, tooltip, and other information).  
A row in the Data structure is represented by a cell in the GridView, not a row.
After the user edits the information, a form (invisible to the user in the main page) is submitted by clicking the form button. It has an "Onclick" which calls a function,that updates the data in the Data class and invokes BindGrid() above.

Functionally this works fine, but the whole page is refreshed on each edit which is inefficient and takes a second or two to load which is undesired from the usability perspective.

Is there another approach I should be taking for the specific cell to be updated without the whole page being refreshed ?

Thanks,
Rinat