Error: Request Entity Too Large: head – when creating validation rule in custom object.

I am creating my Data Model – Created one Custom Object with around 400 fields and 15-20 Validation Rules on it.

Now, When I am trying to add more Validation Rules – It is giving me following error on the complete blank White Screen with following error message in the corner—

Error: Request Entity Too Large: head

Since we have 500 Max limit for fields and 100 for validation rules.