The STUFF() function is useful for concatenating multiple rows in to one string, so it can be used effectively with xml queries to do this as follows:

SELECT STUFF(
        cast(TextField1 as xml).query('for $step in /ChoiceValues/Data/@DisplayText return concat(", ", string($step))')
        .value('.', 'nvarchar(max)'),
    1, 2, '')
 FROM Claims WHERE ID = [Your ID]